Feedback mode indication for coordinated transmission

ABSTRACT

Certain aspects of the present disclosure provide techniques for wireless communication. The techniques include a method wireless communication by a user equipment including receiving a configuration message, wherein the configuration message in part configures the UE to communicate coordinated transmissions with a plurality of transmission reception points using a coordinated transmission mode. The method further includes, receiving one or more physical downlink shared channel transmissions from a plurality of transmission reception points in accordance with the coordinated transmission mode. The method further includes, selecting a HARQ-ACK feedback mode based in part on the coordinated transmission mode. The method further includes, transmitting HARQ-ACK feedback to at least one of the plurality of transmission reception points using the selected HARQ-ACK feedback mode.

CLAIM OF PRIORITY UNDER 35 U.S.C. § 119

The present application for patent claims benefit of U.S. ProvisionalPatent Application Ser. No. 62/711,157, filed Jul. 27, 2018, assigned tothe assignee hereof and hereby expressly incorporated by referenceherein.

FIELD

Aspects of the present disclosure relate to wireless communications, andmore particularly, to techniques for providing differentacknowledgment/negative (ACK/NACK) feedback modes for coordinatedtransmissions from multiple transmission reception points (TRPs).

BACKGROUND

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,broadcasts, etc. These wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power, etc.). Examples of such multiple-access systems include3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE)systems, LTE Advanced (LTE-A) systems, code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems, to name a few.

In some examples, a wireless multiple-access communication system mayinclude a number of base stations (BSs), which are each capable ofsimultaneously supporting communication for multiple communicationdevices, otherwise known as user equipments (UEs). In an LTE or LTE-Anetwork, a set of one or more base stations may define an eNodeB (eNB).In other examples (e.g., in a next generation, a new radio (NR), or 5Gnetwork), a wireless multiple access communication system may include anumber of distributed units (DUs) (e.g., edge units (EUs), edge nodes(ENs), radio heads (RHs), smart radio heads (SRHs), transmissionreception points (TRPs), etc.) in communication with a number of centralunits (CUs) (e.g., central nodes (CNs), access node controllers (ANCs),etc.), where a set of one or more distributed units, in communicationwith a central unit, may define an access node (e.g., which may bereferred to as a base station, 5G NB, next generation NodeB (gNB orgNodeB), TRP, etc.). A base station or distributed unit may communicatewith a set of UEs on downlink channels (e.g., for transmissions from abase station or to a UE) and uplink channels (e.g., for transmissionsfrom a UE to a base station or distributed unit).

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. New Radio (NR) (e.g., 5G) is an exampleof an emerging telecommunication standard. NR is a set of enhancementsto the LTE mobile standard promulgated by 3GPP. It is designed to bettersupport mobile broadband Internet access by improving spectralefficiency, lowering costs, improving services, making use of newspectrum, and better integrating with other open standards using OFDMAwith a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL).To these ends, NR supports beamforming, multiple-input multiple-output(MIMO) antenna technology, and carrier aggregation.

However, as the demand for mobile broadband access continues toincrease, there exists a need for further improvements in NR and LTEtechnology. Preferably, these improvements should be applicable to othermulti-access technologies and the telecommunication standards thatemploy these technologies.

BRIEF SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this disclosure provide advantages that include improvedcommunications between access points and stations in a wireless network.

Certain aspects provide a method wireless communication. The methodgenerally includes receiving a configuration message, wherein theconfiguration message in part configures the UE to communicatecoordinated transmissions with a plurality of transmission receptionpoints (TRPs) using a coordinated transmission mode, receiving one ormore physical downlink shared channel (PDSCH) transmissions from aplurality of transmission reception points (TRPs) in accordance with thecoordinated transmission mode, selecting a hybrid automatic repeatedrequest (HARQ) Acknowledgment (HARQ-ACK) feedback mode, from at leastfirst and second HARQ-ACK feedback modes, based in part on thecoordinated transmission mode, and transmitting HARQ-ACK feedback forthe at least one or more PDSCH transmissions to at least one of theplurality of TRPs using the selected HARQ-ACK feedback mode.

Aspects of the present disclosure provide a method for wirelesscommunication by a network entity. The method generally includes sendinga configuration message to a user equipment (UE), wherein theconfiguration message in part configures the UE to communicatecoordinated transmissions with a plurality of transmission receptionpoints (TRPs) using a coordinated transmission mode, transmitting one ormore physical downlink shared channel (PDSCH) transmissions from aplurality of transmission reception points (TRPs) in accordance with thecoordinated transmission mode, determining a hybrid automatic repeatedrequest (HARQ) Acknowledgment (HARQ-ACK) feedback mode, selected from atleast first and second HARQ-ACK feedback modes, based in part on thecoordinated transmission mode, and receiving HARQ-ACK feedback for theat least one or more PDSCH transmissions to at least one of theplurality of TRPs using the determined HARQ-ACK feedback mode

Certain aspects also provide various apparatus, means, and computerreadable medium for performing the operations described above.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe appended drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the drawings. It is to be noted, however, thatthe appended drawings illustrate only certain typical aspects of thisdisclosure and are therefore not to be considered limiting of its scope,for the description may admit to other equally effective aspects.

FIG. 1 is a block diagram conceptually illustrating an exampletelecommunications system, in accordance with certain aspects of thepresent disclosure.

FIG. 2 is a block diagram illustrating an example logical architectureof a distributed radio access network (RAN), in accordance with certainaspects of the present disclosure.

FIG. 3 is a diagram illustrating an example physical architecture of adistributed RAN, in accordance with certain aspects of the presentdisclosure.

FIG. 4 is a block diagram conceptually illustrating a design of anexample base station (BS) and user equipment (UE), in accordance withcertain aspects of the present disclosure.

FIG. 5 is a diagram showing examples for implementing a communicationprotocol stack, in accordance with certain aspects of the presentdisclosure.

FIG. 6 illustrates an example of a frame format for a new radio (NR)system, in accordance with certain aspects of the present disclosure.

FIG. 7 is a block diagram conceptually illustrating an example wirelesscommunication system, in accordance with certain aspects of the presentdisclosure.

FIG. 8 is a flow diagram for an example feedback system in accordancewith certain aspects of the disclosure.

FIG. 9 is a flow diagram for an example feedback system in accordancewith certain aspects of the disclosure.

FIG. 10 illustrates a communications device that may include variouscomponents configured to perform operations for the techniques disclosedherein in accordance with aspects of the present disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in one aspectmay be beneficially utilized on other aspects without specificrecitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processingsystems, and computer readable mediums for providing differentacknowledgment/negative (ACK/NACK) feedback modes for coordinatedtransmission from multiple transmission reception points (TRPs).

The following description provides examples, and is not limiting of thescope, applicability, or examples set forth in the claims. Changes maybe made in the function and arrangement of elements discussed withoutdeparting from the scope of the disclosure. Various examples may omit,substitute, or add various procedures or components as appropriate. Forinstance, the methods described may be performed in an order differentfrom that described, and various steps may be added, omitted, orcombined. Also, features described with respect to some examples may becombined in some other examples. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition to,or other than, the various aspects of the disclosure set forth herein.It should be understood that any aspect of the disclosure disclosedherein may be embodied by one or more elements of a claim. The word“exemplary” is used herein to mean “serving as an example, instance, orillustration.” Any aspect described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otheraspects.

The techniques described herein may be used for various wirelesscommunication technologies, such as LTE, CDMA, TDMA, FDMA, OFDMA,SC-FDMA and other networks. The terms “network” and “system” are oftenused interchangeably. A CDMA network may implement a radio technologysuch as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRAincludes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implementa radio technology such as Global System for Mobile Communications(GSM). An OFDMA network may implement a radio technology such as NR(e.g. 5G RA), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRAand E-UTRA are part of Universal Mobile Telecommunication System (UMTS).

New Radio (NR) is an emerging wireless communications technology underdevelopment in conjunction with the 5G Technology Forum (5GTF). 3GPPLong Term Evolution (LTE) and LTE-Advanced (LTE-A) are releases of UMTSthat use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described indocuments from an organization named “3rd Generation PartnershipProject” (3GPP). cdma2000 and UMB are described in documents from anorganization named “3rd Generation Partnership Project 2” (3GPP2). Thetechniques described herein may be used for the wireless networks andradio technologies mentioned above as well as other wireless networksand radio technologies. For clarity, while aspects may be describedherein using terminology commonly associated with 3G and/or 4G wirelesstechnologies, aspects of the present disclosure can be applied in othergeneration-based communication systems, such as 5G and later, includingNR technologies.

New radio (NR) access (e.g., 5G technology) may support various wirelesscommunication services, such as enhanced mobile broadband (eMBB)targeting wide bandwidth (e.g., 80 MHz or beyond), millimeter wave (mmW)targeting high carrier frequency (e.g., 25 GHz or beyond), massivemachine type communications MTC (mMTC) targeting non-backward compatibleMTC techniques, and/or mission critical targeting ultra-reliablelow-latency communications (URLLC). These services may include latencyand reliability requirements. These services may also have differenttransmission time intervals (TTI) to meet respective quality of service(QoS) requirements. In addition, these services may co-exist in the samesubframe.

Example Wireless Communications System

FIG. 1 illustrates an example wireless communication network 100 inwhich aspects of the present disclosure may be performed. For example,the wireless communication network 100 may be a New Radio (NR) or 5Gnetwork. For example, a UE 120 in FIG. 1 may be configured to performoperations of FIG. 8 to provide acknowledgment feedback according to oneof different modes for coordinated transmissions from multipletransmission reception points (TRPs). One or more base stations 110 mayconfigure a UE for such operations and may control the multiple TRPsinvolved in the coordinated transmissions (e.g., by performingoperations of FIG. 9).

As illustrated in FIG. 1, the wireless network 100 may include a numberof base stations (BSs) 110 and other network entities. ABS may be astation that communicates with user equipments (UEs). Each BS 110 mayprovide communication coverage for a particular geographic area. In3GPP, the term “cell” can refer to a coverage area of a Node B (NB)and/or a Node B subsystem serving this coverage area, depending on thecontext in which the term is used. In NR systems, the term “cell” andnext generation NodeB (gNB), new radio base station (NR BS), 5G NB,access point (AP), or transmission reception point (TRP) may beinterchangeable. In some examples, a cell may not necessarily bestationary, and the geographic area of the cell may move according tothe location of a mobile BS. In some examples, the base stations may beinterconnected to one another and/or to one or more other base stationsor network nodes (not shown) in wireless communication network 100through various types of backhaul interfaces, such as a direct physicalconnection, a wireless connection, a virtual network, or the like usingany suitable transport network.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular radioaccess technology (RAT) and may operate on one or more frequencies. ARAT may also be referred to as a radio technology, an air interface,etc. A frequency may also be referred to as a carrier, a subcarrier, afrequency channel, a tone, a subband, etc. Each frequency may support asingle RAT in a given geographic area in order to avoid interferencebetween wireless networks of different RATs. In some cases, NR or 5G RATnetworks may be deployed.

A base station (BS) may provide communication coverage for a macro cell,a pico cell, a femto cell, and/or other types of cells. A macro cell maycover a relatively large geographic area (e.g., several kilometers inradius) and may allow unrestricted access by UEs with servicesubscription. A pico cell may cover a relatively small geographic areaand may allow unrestricted access by UEs with service subscription. Afemto cell may cover a relatively small geographic area (e.g., a home)and may allow restricted access by UEs having an association with thefemto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs for usersin the home, etc.). A BS for a macro cell may be referred to as a macroBS. A BS for a pico cell may be referred to as a pico BS. A BS for afemto cell may be referred to as a femto BS or a home BS. In the exampleshown in FIG. 1, the BSs 110 a, 110 b and 110 c may be macro BSs for themacro cells 102 a, 102 b and 102 c, respectively. The BS 110 x may be apico BS for a pico cell 102 x. The BSs 110 y and 110 z may be femto BSsfor the femto cells 102 y and 102 z, respectively. ABS may support oneor multiple (e.g., three) cells.

Wireless communication network 100 may also include relay stations. Arelay station is a station that receives a transmission of data and/orother information from an upstream station (e.g., a BS or a UE) andsends a transmission of the data and/or other information to adownstream station (e.g., a UE or a BS). A relay station may also be aUE that relays transmissions for other UEs. In the example shown in FIG.1, a relay station 110 r may communicate with the BS 110 a and a UE 120r in order to facilitate communication between the BS 110 a and the UE120 r. A relay station may also be referred to as a relay BS, a relay,etc.

Wireless network 100 may be a heterogeneous network that includes BSs ofdifferent types, e.g., macro BS, pico BS, femto BS, relays, etc. Thesedifferent types of BSs may have different transmit power levels,different coverage areas, and different impact on interference in thewireless network 100. For example, macro BS may have a high transmitpower level (e.g., 20 Watts) whereas pico BS, femto BS, and relays mayhave a lower transmit power level (e.g., 1 Watt).

Wireless communication network 100 may support synchronous orasynchronous operation. For synchronous operation, the BSs may havesimilar frame timing, and transmissions from different BSs may beapproximately aligned in time. For asynchronous operation, the BSs mayhave different frame timing, and transmissions from different BSs maynot be aligned in time. The techniques described herein may be used forboth synchronous and asynchronous operation.

A network controller 130 may couple to a set of BSs and providecoordination and control for these BSs. The network controller 130 maycommunicate with the BSs 110 via a backhaul. The BSs 110 may alsocommunicate with one another (e.g., directly or indirectly) via wirelessor wireline backhaul.

The UEs 120 (e.g., 120 x, 120 y, etc.) may be dispersed throughout thewireless network 100, and each UE may be stationary or mobile. A UE mayalso be referred to as a mobile station, a terminal, an access terminal,a subscriber unit, a station, a Customer Premises Equipment (CPE), acellular phone, a smart phone, a personal digital assistant (PDA), awireless modem, a wireless communication device, a handheld device, alaptop computer, a cordless phone, a wireless local loop (WLL) station,a tablet computer, a camera, a gaming device, a netbook, a smartbook, anultrabook, an appliance, a medical device or medical equipment, abiometric sensor/device, a wearable device such as a smart watch, smartclothing, smart glasses, a smart wrist band, smart jewelry (e.g., asmart ring, a smart bracelet, etc.), an entertainment device (e.g., amusic device, a video device, a satellite radio, etc.), a vehicularcomponent or sensor, a smart meter/sensor, industrial manufacturingequipment, a global positioning system device, or any other suitabledevice that is configured to communicate via a wireless or wired medium.Some UEs may be considered machine-type communication (MTC) devices orevolved MTC (eMTC) devices. MTC and eMTC UEs include, for example,robots, drones, remote devices, sensors, meters, monitors, locationtags, etc., that may communicate with a BS, another device (e.g., remotedevice), or some other entity. A wireless node may provide, for example,connectivity for or to a network (e.g., a wide area network such asInternet or a cellular network) via a wired or wireless communicationlink. Some UEs may be considered Internet-of-Things (IoT) devices, whichmay be narrowband IoT (NB-IoT) devices.

Certain wireless networks (e.g., LTE) utilize orthogonal frequencydivision multiplexing (OFDM) on the downlink and single-carrierfrequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDMpartition the system bandwidth into multiple (K) orthogonal subcarriers,which are also commonly referred to as tones, bins, etc. Each subcarriermay be modulated with data. In general, modulation symbols are sent inthe frequency domain with OFDM and in the time domain with SC-FDM. Thespacing between adjacent subcarriers may be fixed, and the total numberof subcarriers (K) may be dependent on the system bandwidth. Forexample, the spacing of the subcarriers may be 15 kHz and the minimumresource allocation (called a “resource block” (RB)) may be 12subcarriers (or 180 kHz). Consequently, the nominal Fast FourierTransfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048 forsystem bandwidth of 1.25, 2.5, 5, 10, or 20 megahertz (MHz),respectively. The system bandwidth may also be partitioned intosubbands. For example, a subband may cover 1.08 MHz (i.e., 6 resourceblocks), and there may be 1, 2, 4, 8, or 16 subbands for systembandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

While aspects of the examples described herein may be associated withLTE technologies, aspects of the present disclosure may be applicablewith other wireless communications systems, such as NR. NR may utilizeOFDM with a CP on the uplink and downlink and include support forhalf-duplex operation using TDD. Beamforming may be supported and beamdirection may be dynamically configured. MIMO transmissions withprecoding may also be supported. MIMO configurations in the DL maysupport up to 8 transmit antennas with multi-layer DL transmissions upto 8 streams and up to 2 streams per UE. Multi-layer transmissions withup to 2 streams per UE may be supported. Aggregation of multiple cellsmay be supported with up to 8 serving cells.

In some examples, access to the air interface may be scheduled, whereina. A scheduling entity (e.g., a base station) allocates resources forcommunication among some or all devices and equipment within its servicearea or cell. The scheduling entity may be responsible for scheduling,assigning, reconfiguring, and releasing resources for one or moresubordinate entities. That is, for scheduled communication, subordinateentities utilize resources allocated by the scheduling entity. Basestations are not the only entities that may function as a schedulingentity. In some examples, a UE may function as a scheduling entity andmay schedule resources for one or more subordinate entities (e.g., oneor more other UEs), and the other UEs may utilize the resourcesscheduled by the UE for wireless communication. In some examples, a UEmay function as a scheduling entity in a peer-to-peer (P2P) network,and/or in a mesh network. In a mesh network example, UEs may communicatedirectly with one another in addition to communicating with a schedulingentity.

In FIG. 1, a solid line with double arrows indicates desiredtransmissions between a UE and a serving BS, which is a BS designated toserve the UE on the downlink and/or uplink. A finely dashed line withdouble arrows indicates interfering transmissions between a UE and a BS.

FIG. 2 illustrates an example logical architecture of a distributedRadio Access Network (RAN) 200, which may be implemented in the wirelesscommunication network 100 illustrated in FIG. 1. A 5G access node 206may include an access node controller (ANC) 202. ANC 202 may be acentral unit (CU) of the distributed RAN 200. The backhaul interface tothe Next Generation Core Network (NG-CN) 204 may terminate at ANC 202.The backhaul interface to neighboring next generation access Nodes(NG-ANs) 210 may terminate at ANC 202. ANC 202 may include one or moretransmission reception points (TRPs) 208 (e.g., cells, BSs, gNBs, etc.).

The TRPs 208 may be a distributed unit (DU). TRPs 208 may be connectedto a single ANC (e.g., ANC 202) or more than one ANC (not illustrated).For example, for RAN sharing, radio as a service (RaaS), and servicespecific AND deployments, TRPs 208 may be connected to more than oneANC. TRPs 208 may each include one or more antenna ports. TRPs 208 maybe configured to individually (e.g., dynamic selection) or jointly(e.g., joint transmission) serve traffic to a UE.

The logical architecture of distributed RAN 200 may support fronthaulingsolutions across different deployment types. For example, the logicalarchitecture may be based on transmit network capabilities (e.g.,bandwidth, latency, and/or jitter).

The logical architecture of distributed RAN 200 may share featuresand/or components with LTE. For example, next generation access node(NG-AN) 210 may support dual connectivity with NR and may share a commonfronthaul for LTE and NR.

The logical architecture of distributed RAN 200 may enable cooperationbetween and among TRPs 208, for example, within a TRP and/or across TRPsvia ANC 202. An inter-TRP interface may not be used.

Logical functions may be dynamically distributed in the logicalarchitecture of distributed RAN 200. As will be described in more detailwith reference to FIG. 5, the Radio Resource Control (RRC) layer, PacketData Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer,Medium Access Control (MAC) layer, and a Physical (PHY) layers may beadaptably placed at the DU (e.g., TRP 208) or CU (e.g., ANC 202).

FIG. 3 illustrates an example physical architecture of a distributedRadio Access Network (RAN) 300, according to aspects of the presentdisclosure. A centralized core network unit (C-CU) 302 may host corenetwork functions. C-CU 302 may be centrally deployed. C-CU 302functionality may be offloaded (e.g., to advanced wireless services(AWS)), in an effort to handle peak capacity.

A centralized RAN unit (C-RU) 304 may host one or more ANC functions.Optionally, the C-RU 304 may host core network functions locally. TheC-RU 304 may have distributed deployment. The C-RU 304 may be close tothe network edge.

A DU 306 may host one or more TRPs (Edge Node (EN), an Edge Unit (EU), aRadio Head (RH), a Smart Radio Head (SRH), or the like). The DU may belocated at edges of the network with radio frequency (RF) functionality.

FIG. 4 illustrates example components of BS 110 and UE 120 (as depictedin FIG. 1), which may be used to implement aspects of the presentdisclosure. For example, antennas 452, processors 466, 458, 464, and/orcontroller/processor 480 of the UE 120 and/or antennas 434, processors420, 460, 438, and/or controller/processor 440 of the BS 110 may be usedto perform the various techniques and methods described herein.

At the BS 110, a transmit processor 420 may receive data from a datasource 412 and control information from a controller/processor 440. Thecontrol information may be for the physical broadcast channel (PBCH),physical control format indicator channel (PCFICH), physical hybrid ARQindicator channel (PHICH), physical downlink control channel (PDCCH),group common PDCCH (GC PDCCH), etc. The data may be for the physicaldownlink shared channel (PDSCH), etc. The processor 420 may process(e.g., encode and symbol map) the data and control information to obtaindata symbols and control symbols, respectively. The processor 420 mayalso generate reference symbols, e.g., for the primary synchronizationsignal (PSS), secondary synchronization signal (SSS), and cell-specificreference signal (CRS). A transmit (TX) multiple-input multiple-output(MIMO) processor 430 may perform spatial processing (e.g., precoding) onthe data symbols, the control symbols, and/or the reference symbols, ifapplicable, and may provide output symbol streams to the modulators(MODs) 432 a through 432 t. Each modulator 432 may process a respectiveoutput symbol stream (e.g., for OFDM, etc.) to obtain an output samplestream. Each modulator may further process (e.g., convert to analog,amplify, filter, and upconvert) the output sample stream to obtain adownlink signal. Downlink signals from modulators 432 a through 432 tmay be transmitted via the antennas 434 a through 434 t, respectively.

At the UE 120, the antennas 452 a through 452 r may receive the downlinksignals from the base station 110 and may provide received signals tothe demodulators (DEMODs) in transceivers 454 a through 454 r,respectively. Each demodulator 454 may condition (e.g., filter, amplify,downconvert, and digitize) a respective received signal to obtain inputsamples. Each demodulator may further process the input samples (e.g.,for OFDM, etc.) to obtain received symbols. A MIMO detector 456 mayobtain received symbols from all the demodulators 454 a through 454 r,perform MIMO detection on the received symbols if applicable, andprovide detected symbols. A receive processor 458 may process (e.g.,demodulate, deinterleave, and decode) the detected symbols, providedecoded data for the UE 120 to a data sink 460, and provide decodedcontrol information to a controller/processor 480.

On the uplink, at UE 120, a transmit processor 464 may receive andprocess data (e.g., for the physical uplink shared channel (PUSCH)) froma data source 462 and control information (e.g., for the physical uplinkcontrol channel (PUCCH) from the controller/processor 480. The transmitprocessor 464 may also generate reference symbols for a reference signal(e.g., for the sounding reference signal (SRS)). The symbols from thetransmit processor 464 may be precoded by a TX MIMO processor 466 ifapplicable, further processed by the demodulators in transceivers 454 athrough 454 r (e.g., for SC-FDM, etc.), and transmitted to the basestation 110. At the BS 110, the uplink signals from the UE 120 may bereceived by the antennas 434, processed by the modulators 432, detectedby a MIMO detector 436 if applicable, and further processed by a receiveprocessor 438 to obtain decoded data and control information sent by theUE 120. The receive processor 438 may provide the decoded data to a datasink 439 and the decoded control information to the controller/processor440.

The controllers/processors 440 and 480 may direct the operation at thebase station 110 and the UE 120, respectively. The processor 440 and/orother processors and modules at the BS 110 may perform or direct theexecution of processes for the techniques described herein. The memories442 and 482 may store data and program codes for BS 110 and UE 120,respectively. A scheduler 444 may schedule UEs for data transmission onthe downlink and/or uplink.

FIG. 5 illustrates a diagram 500 showing examples for implementing acommunications protocol stack, according to aspects of the presentdisclosure. The illustrated communications protocol stacks may beimplemented by devices operating in a wireless communication system,such as a 5G system (e.g., a system that supports uplink-basedmobility). Diagram 500 illustrates a communications protocol stackincluding a Radio Resource Control (RRC) layer 510, a Packet DataConvergence Protocol (PDCP) layer 515, a Radio Link Control (RLC) layer520, a Medium Access Control (MAC) layer 525, and a Physical (PHY) layer530. In various examples, the layers of a protocol stack may beimplemented as separate modules of software, portions of a processor orASIC, portions of non-collocated devices connected by a communicationslink, or various combinations thereof. Collocated and non-collocatedimplementations may be used, for example, in a protocol stack for anetwork access device (e.g., ANs, CUs, and/or DUs) or a UE.

A first option 505-a shows a split implementation of a protocol stack,in which implementation of the protocol stack is split between acentralized network access device (e.g., an ANC 202 in FIG. 2) anddistributed network access device (e.g., DU 208 in FIG. 2). In the firstoption 505-a, an RRC layer 510 and a PDCP layer 515 may be implementedby the central unit, and an RLC layer 520, a MAC layer 525, and a PHYlayer 530 may be implemented by the DU. In various examples the CU andthe DU may be collocated or non-collocated. The first option 505-a maybe useful in a macro cell, micro cell, or pico cell deployment.

A second option 505-b shows a unified implementation of a protocolstack, in which the protocol stack is implemented in a single networkaccess device. In the second option, RRC layer 510, PDCP layer 515, RLClayer 520, MAC layer 525, and PHY layer 530 may each be implemented bythe AN. The second option 505-b may be useful in, for example, a femtocell deployment.

Regardless of whether a network access device implements part or all ofa protocol stack, a UE may implement an entire protocol stack as shownin 505-c (e.g., the RRC layer 510, the PDCP layer 515, the RLC layer520, the MAC layer 525, and the PHY layer 530).

In LTE, the basic transmission time interval (TTI) or packet duration isthe 1 ms subframe. In NR, a subframe is still 1 ms, but the basic TTI isreferred to as a slot. A subframe contains a variable number of slots(e.g., 1, 2, 4, 8, 16, . . . slots) depending on the subcarrier spacing.The NR RB is 12 consecutive frequency subcarriers. NR may support a basesubcarrier spacing of 15 KHz and other subcarrier spacing may be definedwith respect to the base subcarrier spacing, for example, 30 kHz, 60kHz, 120 kHz, 240 kHz, etc. The symbol and slot lengths scale with thesubcarrier spacing. The CP length also depends on the subcarrierspacing.

FIG. 6 is a diagram showing an example of a frame format 600 for NR. Thetransmission timeline for each of the downlink and uplink may bepartitioned into units of radio frames. Each radio frame may have apredetermined duration (e.g., 10 ms) and may be partitioned into 10subframes, each of 1 ms, with indices of 0 through 9. Each subframe mayinclude a variable number of slots depending on the subcarrier spacing.Each slot may include a variable number of symbol periods (e.g., 7 or 14symbols) depending on the subcarrier spacing. The symbol periods in eachslot may be assigned indices. A mini-slot, which may be referred to as asub-slot structure, refers to a transmit time interval having a durationless than a slot (e.g., 2, 3, or 4 symbols).

Each symbol in a slot may indicate a link direction (e.g., DL, UL, orflexible) for data transmission and the link direction for each subframemay be dynamically switched. The link directions may be based on theslot format. Each slot may include DL/UL data as well as DL/UL controlinformation.

In NR, a synchronization signal (SS) block is transmitted. The SS blockincludes a PSS, a SSS, and a two symbol PBCH. The SS block can betransmitted in a fixed slot location, such as the symbols 0-3 as shownin FIG. 6. The PSS and SSS may be used by UEs for cell search andacquisition. The PSS may provide half-frame timing, the SS may providethe CP length and frame timing. The PSS and SSS may provide the cellidentity. The PBCH carries some basic system information, such asdownlink system bandwidth, timing information within radio frame, SSburst set periodicity, system frame number, etc. The SS blocks may beorganized into SS bursts to support beam sweeping. Further systeminformation such as, remaining minimum system information (RMSI), systeminformation blocks (SIBs), other system information (OSI) can betransmitted on a physical downlink shared channel (PDSCH) in certainsubframes.

In some circumstances, two or more subordinate entities (e.g., UEs) maycommunicate with each other using sidelink signals. Real-worldapplications of such sidelink communications may include public safety,proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V)communications, Internet of Everything (IoE) communications, IoTcommunications, mission-critical mesh, and/or various other suitableapplications. Generally, a sidelink signal may refer to a signalcommunicated from one subordinate entity (e.g., UE1) to anothersubordinate entity (e.g., UE2) without relaying that communicationthrough the scheduling entity (e.g., UE or BS), even though thescheduling entity may be utilized for scheduling and/or controlpurposes. In some examples, the sidelink signals may be communicatedusing a licensed spectrum (unlike wireless local area networks, whichtypically use an unlicensed spectrum).

A UE may operate in various radio resource configurations, including aconfiguration associated with transmitting pilots using a dedicated setof resources (e.g., a radio resource control (RRC) dedicated state,etc.) or a configuration associated with transmitting pilots using acommon set of resources (e.g., an RRC common state, etc.). Whenoperating in the RRC dedicated state, the UE may select a dedicated setof resources for transmitting a pilot signal to a network. Whenoperating in the RRC common state, the UE may select a common set ofresources for transmitting a pilot signal to the network. In eithercase, a pilot signal transmitted by the UE may be received by one ormore network access devices, such as an AN, or a DU, or portionsthereof. Each receiving network access device may be configured toreceive and measure pilot signals transmitted on the common set ofresources, and also receive and measure pilot signals transmitted ondedicated sets of resources allocated to the UEs for which the networkaccess device is a member of a monitoring set of network access devicesfor the UE. One or more of the receiving network access devices, or a CUto which receiving network access device(s) transmit the measurements ofthe pilot signals, may use the measurements to identify serving cellsfor the UEs, or to initiate a change of serving cell for one or more ofthe UEs.

Example Feedback Mode Indication for Coordinated Transmission

Aspects of the present disclosure provide apparatus, methods, processingsystems, and computer program products that enable a UE to selectdifferent acknowledgment/negative (ACK/NACK) feedback modes fordifferent types of coordinated transmission modes. In certain aspects, aUE can communicate with a plurality of TRPs at the same time, or atdifferent times (e.g., in a non-coherent/non-transparent manner (i.e.,non-coherent joint transmission (NCJT)).

FIG. 7 depicts a wireless communication system 700 in accordance withcertain aspects of the disclosure. FIG. 7 includes a UE 710 and aplurality of transmission reception points (TRPs) 702 a-702 d (orcollectively TRPs 702). TRPs 702 may be coupled by a network controller(not shown) to provide coordination and control for TRPs 702. Thenetwork controller may communicate with the TRPs 702 via a backhaul. TheTRPs 702 may also communicate with one another (e.g., directly orindirectly) via wireless or wireline backhaul.

In certain aspects, a backhaul condition is indicative of a highperformance backhaul or indicative of low performance backhaul. Abackhaul condition is indicative of a high performance backhaul when thecapacity of the backhaul between TRPs (e.g., backhaul 706 a coupling TRP702 a and TRP 702 c) is not substantially constrained (e.g., backhaul706 a has substantially unlimited capacity) and the latency between TRPs(e.g., TRP 702 a and TRP 702 c) is substantially low (e.g., less thanabout 1 millisecond).

A backhaul condition is indicative of a low performance backhaul whenthe capacity of the backhaul between TRPs (e.g., backhaul 704 couplingTPR 702 a and TRP 702 d) is constrained (e.g., backhaul 704 has asubstantially limited capacity) and the latency between TRPs (e.g., TPR702 a and TRP 702 d) is not substantially low (e.g., greater than about5 milliseconds). It will be appreciated that in certain aspects, a UE(e.g., UE 710) may be in communication with more than one TRP (e.g., TRP702 a, 702 c, and 702 d) and the backhaul condition may be indicative ofa mixed backhaul condition (e.g., a first backhaul 704 is indicative ofa low performance backhaul between TRP 702 a and 702 d, and a secondbackhaul 706 a is indicative of a high performance backhaul between TRP702 a and 702 d). In certain aspects, when a backhaul condition isindicative of a mixed backhaul condition, the backhaul condition istreated as a low performance backhaul. In some cases, a UE may besignaled certain parameters indicative of the backhaul condition (e.g.,an actual backhaul delay experienced between TRPs and/or some otherparameter indicative of delay).

In certain aspects, multiple coordinated transmission modes may be usedby a UE (e.g., UE 710) to communicate coordinated transmissions with aplurality of TRPs (e.g., TRP 702 a, 702 c, and 702 d). It will beappreciated that the UE may first receive a configuration message (e.g.,a radio resource control (RRC) message) that in part configures the UEto communicate coordinated transmissions with the plurality of TRPs. Inother aspects, the UE may be preconfigured to communicate coordinatedtransmissions with the plurality of TRPs.

Aspects of the present disclosure provide ACK/NACK (HARQ-ACK) feedbackmodes that may be suitable for different backhaul conditions. TheACK/NACK feedback modes described herein may be used with a variety ofdifferent coordinated transmission modes. While certain examplecoordinated transmission modes are described in accordance with aspectsof the present disclosure (e.g., the six coordinated transmission modesdescribed below) this disclosure can apply to other transmission modes.

A first coordinated transmission mode (or first mode) may be used when aphysical downlink control channel (PDCCH) and a physical downlink sharedchannel (PDSCH) are sent from a plurality of TRPs (e.g., TRP 702 a andTRP 702 c) to a UE (e.g., UE 710), and the PDSCH includes differentspatial layers from different TRPs (e.g., a first spatial layer from TRP702 a and a second spatial layer from TRP 702 c).

A second coordinated transmission mode (or second mode) may be used whena first PDCCH, a second PDCCH, a first PDSCH, and a second PDSCH aretransmitted from different TRPs (e.g., TRP 702 a and TRP 702 c, or TRP702 a and TRP 702 d) to a UE (e.g., UE 710), and each of the first PDSCHand a second PDSCH carry different transport blocks.

A third coordinated transmission mode (or third mode) may be used when afirst PDCCH, a second PDCCH, a first PDSCH, and a second PDSCH aretransmitted from different TRPs (e.g., TRP 702 a and TRP 702 c) to a UE(e.g., UE 710), and the first PDSCH and the second PDSCH carry the sametransport block. This transmission mode may be interpreted as PDSCHrepetition.

A fourth coordinated transmission mode (or fourth mode) may be used whena PDCCH repetition is sent from the plurality of TRPs (e.g., TRP 702 aand TRP 702 c) to a UE (e.g., UE 710), wherein multiple PDCCHs aretransmitted from different TRPs (e.g., multiple PDCCHs from TRP 702 aand multiple PDCCHs from TRP 702 c), and each of the PDCCHs carry thesame downlink control information and schedule for a PDSCH.

A fifth coordinated transmission mode (or fifth mode) may be used when aPDCCH, a first PDSCH, and a second PDSCH are transmitted from differentTRPs (e.g., TRP 702 a and TRP 702 c) to a UE (e.g., UE 710), and thefirst PDSCH and the second PDSCH carry the same transport block. In thistransmission mode, the first PDSCH and the second PDSCH are bothscheduled by the PDCCH.

A sixth coordinated transmission mode (or sixth mode) may be used when aPDCCH, a first PDSCH, and a second PDSCH are transmitted from differentTRPs (e.g., TRP 702 a and TRP 702 c) to a UE (e.g., UE 710), and thefirst PDSCH and the second PDSCH carry different transport blocks. Inthis transmission mode, the first PDSCH and the second PDSCH are bothscheduled by the PDCCH.

FIG. 8 shows example operations 800 of a method of wirelesscommunication performed at a user equipment (UE) in accordance withcertain aspects of the disclosure. Operations 800 may be performed, forexample, by UE 710 in FIG. 7, to select an ACK/NACK feedback mode basedfor coordinate transmissions from multiple TRPs.

Operations 800 begin, at 802, by receiving a configuration message,wherein the configuration message in part configures the UE tocommunicate coordinated transmissions with a plurality of TRPs (e.g.,TRPs 702 in FIG. 7) using a coordinated transmission mode.

At 804, the UE receives one or more physical downlink shared channel(PDSCH) transmissions from the plurality of TRPs in accordance with thecoordinated transmission mode.

At 806, the UE selects a hybrid automatic repeated request (HARD)Acknowledgment (HARQ-ACK) feedback mode based in part on a coordinatedtransmission mode (e.g., one of a first mode, a second mode a thirdmode, a fourth mode, a fifth mode, or a sixth mode).

At 808, the UE transmits HARQ-ACK feedback to at least one of theplurality of TRPs using the selected HARQ-ACK feedback mode.

FIG. 9 shows example operations 900 of a method of wirelesscommunication performed at a network entity, in accordance with certainaspects of the disclosure. Operations 900 may be performed, for example,by a TRP 702 in FIG. 7 (or network entity in control thereof), toconfigure (communicate with) a UE performing operations 800 of FIG. 8.

Operations 900 begin, at 902, by sending a configuration message to auser equipment (UE), wherein the configuration message in partconfigures the UE to communicate coordinated transmissions with aplurality of transmission reception points (TRPs) using a coordinatedtransmission mode.

At 904, the network entity transmits one or more physical downlinkshared channel (PDSCH) transmissions from a plurality of transmissionreception points (TRPs) in accordance with the coordinated transmissionmode.

At 906, the network entity determines a hybrid automatic repeatedrequest (HARD) Acknowledgment (HARQ-ACK) feedback mode, selected from atleast first and second HARQ-ACK feedback modes, based in part on thecoordinated transmission mode.

At 908, the network entity receives HARQ-ACK feedback for the at leastone or more PDSCH transmissions to at least one of the plurality of TRPsusing the determined HARQ-ACK feedback mode.

In certain aspects, a HARQ-ACK feedback mode may be one of a firstACK/NACK feedback mode (e.g., a joint HARQ-ACK feedback mode) or asecond ACK/NACK feedback mode (e.g., a separate HARQ-ACK feedback mode).A joint feedback mode is characterized by using either a joint ACK/NACKfeedback across a plurality of TRPs (e.g., using a joint codebook) or bymultiplexing one or more ACK/NACK (HARQ-ACK) feedbacks (e.g., whereineach is generated from one or more codebooks) into a joint transmission.In some cases, when the UE generates the ACK/NACK feedback(s) for thereceived PDSCH transmissions, it may first determine the TRP from whichthe PDSCH(s) are transmitted. Based on this determination, it may thengenerate a first codebook (including ACK/NACKs). In some cases, the UEmay generate two HARQ-ACK codebooks and transmit both of them to both ofthe TRPs.

In certain aspects, when the coordinated transmission mode is one of thefirst mode, fourth mode, third mode, fifth mode, or sixth mode, thejoint feedback mode is used. In certain aspects, the UE determines touse the joint feedback mode based in part on determining that thecoordinated transmission mode indicated in the configuration message inblock 802 is one of a first mode, fourth mode, third mode, fifth mode,or sixth mode is configured. It will be appreciated that the jointfeedback mode may be used when there is a high performance backhaulcondition between all TRPs.

In certain aspects, a separate feedback mode is characterized byseparate ACK/NACK feedback for each TRP (e.g., using a separate codebookfor each TRP to generate an ACK/NACK for each respective TRP). Forexample, a UE may receive PDSCH from different TRPs, determines theTRP(s) from which the PDSCHs are transmitted. Based on thisdetermination, the UE may generate separate HARQ-ACK codebooks forHARQ-ACK feedbacks corresponding to the respective PDSCHs. The UE maythen feed back the respective HARQ-ACK codebooks separately to each TRP,In certain aspects, when a UE is configured with a certain coordinatedtransmission mode (e.g. the second mode), both the joint feedback modeand the separate feedback mode may be used.

In certain aspects (e.g., when the UE is configured for the secondmode), when a backhaul condition is indicative of a high performancebackhaul the joint feedback mode is used, and the separate feedback modeis used when a backhaul condition is indicative of low performancebackhaul. In certain aspects, when a backhaul condition is indicative ofa mixed backhaul condition of high performance backhaul and lowperformance backhaul, the TRPs may be clustered into several groups,wherein the TRPs within each group are connected via high performancebackhauls, and the TRPs in different groups may be connected via lowperformance backhauls. In this case, separate feedback mode is usedtowards each group of groups of TRPs, and a joint feedback mode is usedfor ACK/NACK feedback to TRPs within the same group.

In certain aspects (e.g., when the UE is configured for the secondmode), the UE may receive in a configuration message (e.g., a RRCmessage) and select the ACK/NACK feedback mode based in part oninformation contained in the RRC message (e.g., information indicativeof a joint feedback mode or a separate feedback mode).

In certain aspects (e.g., when the UE is configured for the secondmode), the UE may receive in a configuration message, wherein theconfiguration message in part indicates at least one downlink controlinformation (DCI) indicative of a first codebook. In this case, the UEmay receive at least one DCI from at least one of a plurality of theTRPs and select a codebook based on the at least one DCI. The UE maygenerate ACK/NACK feedback from the indicated codebook and transmit thegenerated ACK/NACK feedback to the plurality of the TRPs.

It will be appreciated that in certain aspects, the DCI may beconfigured with a field for information indicative of a first codebook,but in certain cases, this field is not configured in the DCI. When theUE determined that the field remains unused, it uses a joint feedbackmode. When the UE determined that the filed is not configured in theDCI, it may use a separate feedback mode. It will be further appreciatedthat the field for information indicative of a codebook, which incertain aspects is a hybrid automatic repeated request (HARD) codebookindicator, is a new field which may be configured in a DCI.

In certain aspects, the at least one DCI may be indicative of a firstfeedback mode (e.g., a joint feedback mode) or a second feedback mode(e.g., a separate feedback mode). In this case, the UE may select thefirst feedback mode or the second feedback mode based in part on theDCI. For example, the DCI may be indicative of a first codebook and thefirst codebook is indicative of the second ACK/NACK feedback mode, thusthe UE selects the second feedback mode (e.g., a separate feedbackmode).

It will be appreciated that there are static (or semi-static codebooks)(e.g., a codebook where the size of the codebook does not change duringtransmissions) and dynamic codebooks (e.g., a codebook where number ofACK/NACK bits in each ACK/NACK feedback may vary from transmission totransmission, and the number of ACK/NACK bits is signaled in a DCI viathe DAI (downlink assignment indicator) field)). It will be furtherappreciated that in accordance with certain aspects of the disclosure,ACK/NACK feedback from both semi-static codebooks and dynamic codebooksare supported. It other aspects, ACK/NACK feedback from only semi-staticcodebooks or dynamic codebooks are supported.

In certain aspects, the UE may autonomously determine an ACK/NACKfeedback mode based on one or more configuration parameters (e.g.,number of codebooks, codebook sizing, codebook information, etc.)indicative of a joint feedback mode or a separate feedback mode. Forexample, a UE may be configured with a single semi-static code book ormultiple semi-static code books. In certain aspects, when the UE isconfigured with a single semi-static codebook, the UE implicitlydetermines to use a joint feedback mode. In other aspects, a UE mayimplicitly determine to use a separate feedback mode when the UE isconfigured with multiple semi-static codebooks.

In certain aspects (e.g., when the UE is configured for the secondmode), and the UE selects the second feedback mode (e.g., a separatefeedback mode), the UE may determine a PUCCH transmission resource forat least one ACK/NACK feedback. For example, when the UE determines afirst PUCCH transmission to a first TRP and a second PUCCH transmissionto a second TRP are scheduled on the same PUCCH resource, the UE cangenerate a first ACK/NACK feedback from a first codebook and a secondACK/NACK feedback from a second codebook. The UE can then multiplex thefirst ACK/NACK feedback and the second ACK/NACK feedback (e.g., a firstnumber of bits X are used for the first TRP and a second number of bitsY are used for the second TRP (e.g., where X and Y are in certainaspects each a RRC configured size). The UE may then transmit themultiplexed ACK/NACK feedback to the plurality of TRPs on the PUCCHresource (e.g., based on a pre-determined (semi-static) order, with asize (e.g., number of ACK/NACK bits) that equals the sum of size of themultiplexed ACK/NACK feedback).

In certain aspect, after multiplexing, the PUCCH may need to betransmitted on a different resource than the scheduled PUCCH resource(e.g., due to a change in payload size (e.g., comparing either X or Y toX+Y)). In other aspects, the network may configure PUCCH resource setsand the codebook sizes such that a resource change is not needed (e.g.,a PUCCH resource for X is sufficient for X+Y). It will be appreciatedthat the first TRP and the second TRP may detect (e.g., using blinddetection) and determine if there is more than one codebook (e.g., basedin part on one or more codebook size) to determine information specificto each TRP.

In certain aspects, (e.g., when the UE is configured for the secondmode), UE may be configured with multiple semi-static codebooks, one forACK/NACK feedback to each TRP. In addition, the size of each semi-staticcodebook may be different (e.g., corresponding to X and Y discussedabove). Thus, it will be appreciated a TRP can determine if there is amultiplexed transmission using codebook sizes information.

For example, when a first codebook size X and a second codebook size Yare based on different semi-static codebooks, wherein X is a differentsize than Y, then a TRP can determine the first codebook size X isassociated with a TRP A and the second codebook size Y is associatedwith a TRP B. It will be appreciated that semi-static coordinationbetween the TRPs (e.g., each TRP can access information indicative ofeach of the different codebooks associated with each TRP) is used by aTRP to determine the codebook sizes associated with one or more otherTRPs.

In certain aspects (e.g., when the UE is configured for the third mode),the UE receives a first PDCCH from a first TRP associated with a firstDCI, and the UE receives a second PDCCH from a second TRP associatedwith a second DCI, wherein each DCI is indicative of transmission of thesame transport block (TB). In this case, the UE may be constrained toonly use one PUCCH for ACK/NACK feedback corresponding to the TB.

In certain aspects, when the two DCI's do not contain the sameinformation associated with ACK/NACK feedback (e.g., slot timing value(k1), downlink assignment index (DAI), ACK/NACK resource indicator (ARI)values, etc.), the UE is configured to treat this as an error case andrefrain from sending ACK/NACK feedback to the first or second TRP. Inother aspects, when two DCI's do not contain the same information (e.g.,k1, DAI, ARI values, etc.), the UE may select one of the DCI's todetermine the PUCCH resources. For example, the UE may select one of theDCIs based on a DCI order, a DCI aggregation level, or a controlresource set identification (CORESET ID). For example, UE may follow theindication in the last DCI in accordance with the order of the PDCCHmonitoring occasion, in order to determine the information (e.g., k1,DAI, ARI value). In another example, the UE may follow the indication inthe DCI that is received in a particular CORSET (e.g., based on CORSETID).

In certain aspects (e.g., when the UE is configured for the second orthird mode), the UE can select a physical uplink control channel (PUCCH)resource based in part on the index of one or more control channelelements (CCE) in the one or more PDCCHs. In this case, the UE maytransmit ACK/NACK feedback on the selected PUCCH resource.

In other aspects, the UE selects the PUCCH resource based on at leastone of a CCE order, a PDCCH monitoring occasion order, a PDCCHaggregation level, or a control resource set identification (CORESETID). In certain aspects, a CCE order is an ordering of the CCE accordingto the resource block index and OFDM symbol index. It will beappreciated that in certain aspects, a PDCCH monitoring occasion orderis an ordering of PDCCH monitoring occasions based on a cell ID andsearch space ID for the UE to monitor PDCCH. For example, UE maydetermine to use the starting CCE of the PDCCH detected in the lastPDCCH monitoring occasion in accordance with the PDCCH monitoringoccasion order to derive a PUCCH resource. It will be appreciated thatthis can resolve a potential ambiguity for the starting CCE used toderive a PUCCH resource when a UE receives two PDCCHs to jointly triggerone ACK/NACK feedback. Thus, in this case, a UE can determine the PUCCHresource even when implicit mapping is used for PUCCH resourceidentification.

FIG. 10 illustrates a communications device 1000 that may includevarious components (e.g., corresponding to means-plus-functioncomponents) configured to perform operations for the techniquesdisclosed herein, such as the operations illustrated in FIG. 8 and/orFIG. 9. The communications device 1000 includes a processing system 1002coupled to a transceiver 1008. The transceiver 1008 is configured totransmit and receive signals for the communications device 1000 via anantenna 1010, such as the various signal described herein. Theprocessing system 1002 may be configured to perform processing functionsfor the communications device 1000, including processing signalsreceived and/or to be transmitted by the communications device 1000.

The processing system 1002 includes a processor 1004 coupled to acomputer-readable medium/memory 1012 via a bus 1006. In certain aspects,the computer-readable medium/memory 1012 is configured to storeinstructions that when executed by processor 1004, cause the processor1004 to perform the operations illustrated in FIG. 8 and/or FIG. 9, orother operations for performing the various techniques discussed herein.

In certain aspects, the processing system 1002 further includes areceiving component 1014 for performing the operations illustrated inFIG. 8 blocks 802 and 804 (or FIG. 9 block 908). Additionally, theprocessing system 1002 includes a selecting/determining component 1016for performing the operations illustrated in FIG. 8 block 806 (or FIG. 9block 906). Additionally, the processing system 1002 includes atransmitting component 1018 for performing the operations illustrated inFIG. 8 block 808 (or FIG. 9 blocks 902 and 904).

The receiving component 1014, selecting component 1016, and transmittingcomponent 1018 may be coupled to the processor 1004 via bus 1006. Incertain aspects, the receiving component 1014, selecting component 1016,and transmitting component 1018 may be hardware circuits. In certainaspects, the receiving component 1014, selecting component 1016, andtransmitting component 1018 may be software components that are executedand run on processor 1004.

The methods disclosed herein comprise one or more steps or actions forachieving the methods. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language of the claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedthroughout this disclosure that are known or later come to be known tothose of ordinary skill in the art are expressly incorporated herein byreference and are intended to be encompassed by the claims. Moreover,nothing disclosed herein is intended to be dedicated to the publicregardless of whether such disclosure is explicitly recited in theclaims. No claim element is to be construed under the provisions of 35U. S.C. § 112(f) unless the element is expressly recited using thephrase “means for” or, in the case of a method claim, the element isrecited using the phrase “step for.”

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrated circuit (ASIC), or processor. Generally,where there are operations illustrated in figures, those operations mayhave corresponding counterpart means-plus-function components withsimilar numbering.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

If implemented in hardware, an example hardware configuration maycomprise a processing system in a wireless node. The processing systemmay be implemented with a bus architecture. The bus may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system and the overall design constraints.The bus may link together various circuits including a processor,machine-readable media, and a bus interface. The bus interface may beused to connect a network adapter, among other things, to the processingsystem via the bus. The network adapter may be used to implement thesignal processing functions of the PHY layer. In the case of a userterminal 120 (see FIG. 1), a user interface (e.g., keypad, display,mouse, joystick, etc.) may also be connected to the bus. The bus mayalso link various other circuits such as timing sources, peripherals,voltage regulators, power management circuits, and the like, which arewell known in the art, and therefore, will not be described any further.The processor may be implemented with one or more general-purpose and/orspecial-purpose processors. Examples include microprocessors,microcontrollers, DSP processors, and other circuitry that can executesoftware. Those skilled in the art will recognize how best to implementthe described functionality for the processing system depending on theparticular application and the overall design constraints imposed on theoverall system.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer readable medium.Software shall be construed broadly to mean instructions, data, or anycombination thereof, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. The processor may beresponsible for managing the bus and general processing, including theexecution of software modules stored on the machine-readable storagemedia. A computer-readable storage medium may be coupled to a processorsuch that the processor can read information from, and write informationto, the storage medium. In the alternative, the storage medium may beintegral to the processor. By way of example, the machine-readable mediamay include a transmission line, a carrier wave modulated by data,and/or a computer readable storage medium with instructions storedthereon separate from the wireless node, all of which may be accessed bythe processor through the bus interface. Alternatively, or in addition,the machine-readable media, or any portion thereof, may be integratedinto the processor, such as the case may be with cache and/or generalregister files. Examples of machine-readable storage media may include,by way of example, RAM (Random Access Memory), flash memory, ROM (ReadOnly Memory), PROM (Programmable Read-Only Memory), EPROM (ErasableProgrammable Read-Only Memory), EEPROM (Electrically ErasableProgrammable Read-Only Memory), registers, magnetic disks, opticaldisks, hard drives, or any other suitable storage medium, or anycombination thereof. The machine-readable media may be embodied in acomputer-program product.

A software module may comprise a single instruction, or manyinstructions, and may be distributed over several different codesegments, among different programs, and across multiple storage media.The computer-readable media may comprise a number of software modules.The software modules include instructions that, when executed by anapparatus such as a processor, cause the processing system to performvarious functions. The software modules may include a transmissionmodule and a receiving module. Each software module may reside in asingle storage device or be distributed across multiple storage devices.By way of example, a software module may be loaded into RAM from a harddrive when a triggering event occurs. During execution of the softwaremodule, the processor may load some of the instructions into cache toincrease access speed. One or more cache lines may then be loaded into ageneral register file for execution by the processor. When referring tothe functionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

Also, any connection is properly termed a computer-readable medium. Forexample, if the software is transmitted from a website, server, or otherremote source using a coaxial cable, fiber optic cable, twisted pair,digital subscriber line (DSL), or wireless technologies such as infrared(IR), radio, and microwave, then the coaxial cable, fiber optic cable,twisted pair, DSL, or wireless technologies such as infrared, radio, andmicrowave are included in the definition of medium. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, in some aspects computer-readable media maycomprise non-transitory computer-readable media (e.g., tangible media).In addition, for other aspects computer-readable media may comprisetransitory computer-readable media (e.g., a signal). Combinations of theabove should also be included within the scope of computer-readablemedia.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer-readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For example, instructions for performing the operationsdescribed herein and illustrated in FIG. 8.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

What is claimed is:
 1. A method for wireless communication by a userequipment (UE), comprising: receiving a first configuration message anda second configuration message, wherein: the first configurationmessage, in part, configures the UE to communicate coordinatedtransmissions with a plurality of transmission reception points (TRPs)using a coordinated transmission mode, the second configuration messageincludes an indication of a first hybrid automatic repeated requestacknowledgment (HARQ-ACK) feedback mode or a second HARQ-ACK feedbackmode, and the first configuration message and the second configurationmessage are radio resource control (RRC) messages; receiving one or morephysical downlink shared channel (PDSCH) transmissions from the TRPs inaccordance with the coordinated transmission mode; selecting a HARQ-ACKfeedback mode, from at least the first HARQ-ACK feedback and secondHARQ-ACK feedback mode, based on the indication in the secondconfiguration message; and transmitting HARQ-ACK feedback for the atleast one or more PDSCH transmissions to at least one of the pluralityof TRPs using the selected HARQ-ACK feedback mode.
 2. The method ofclaim 1, wherein: the first HARQ-ACK feedback mode comprises a jointHARQ-ACK feedback mode; and the second HARQ-ACK feedback mode comprisesa separate HARQ-ACK feedback mode.
 3. The method of claim 2, furthercomprising: generating HARQ-ACK feedback using a joint codebook when thefirst HARQ-ACK feedback mode is selected; and transmitting the generatedHARQ-ACK feedback to the plurality of TRPs.
 4. The method of claim 2,further comprising generating a first HARQ-ACK feedback from a firstcodebook and a second HARQ-ACK feedback from a second codebook when thesecond HARQ-ACK feedback mode is selected.
 5. The method of claim 4,further comprising transmitting the first HARQ-ACK feedback to a firstTRP, and the second HARQ-ACK feedback to a second TRP.
 6. The method ofclaim 4, wherein the first codebook is a semi-static codebook of a firstsize and the second codebook is a semi-static codebook of a second sizethat is different from the first size.
 7. The method of claim 1, whereinthe coordinated transmission mode is one of: a first mode comprising aphysical downlink control channel (PDCCH) and a PDSCH, wherein the PDSCHcomprises different spatial layers from different TRPs; or a second modecomprising a first PDCCH, a second PDCCH, a first PDSCH and a secondPDSCH, wherein the first PDSCH is transmitted from a first TRP, and thesecond PDSCH is transmitted from a second TRP, and the first PDSCH andthe second PDSCH carry different transport blocks (TBs).
 8. The methodof claim 7, wherein: when the coordinated transmission mode is one of afirst set of transmission modes including the first mode, selecting theHARQ feedback mode comprises selecting the first HARQ-ACK feedback mode;and when the coordinated transmission mode is one of a second set oftransmission modes including the second mode, selecting the HARQfeedback mode comprises selecting comprises selecting the first HARQ-ACKfeedback mode or the second HARQ-ACK feedback mode based at least inpart on one or more parameters.
 9. The method of claim 8, wherein: theone or more parameters indicate a backhaul condition; and when theparameters indicate a high performance backhaul condition, selecting theHARQ feedback mode comprises selecting the first HARQ-ACK feedback mode,and when the one or more parameters indicate a low performance backhaulcondition, selecting the HARQ feedback mode comprises selecting thesecond HARQ-ACK feedback mode.
 10. The method of claim 1, wherein theconfiguration message in part indicates at least one downlink controlinformation (DCI) indicative of a first codebook and the methodcomprises: receiving at least one DCI from at least one of the pluralityof TRPs; selecting the first codebook based on the at least one DCI;generating HARQ-ACK feedback from the first codebook; and transmittingthe HARQ-ACK feedback to the plurality of TRPs.
 11. The method of claim10, wherein the at least one DCI is indicative of the first HARQ-ACKfeedback mode or the second HARQ-ACK feedback mode.
 12. The method ofclaim 11, wherein: when the at least one DCI is indicative of a firstcodebook and the first codebook is indicative of the second HARQ-ACKfeedback mode, selecting the HARQ feedback mode comprises selecting thesecond HARQ-ACK feedback mode.
 13. The method of claim 10, furthercomprising: when two or more of the at least one DCI contain differentinformation, selecting one of the DCIs based on a DCI order, DCIaggregation level, or control resource set identification (CORESET ID),wherein transmitting HARQ-ACK feedback is based on information containedin the selected DCI.
 14. The method of claim 1, further comprising:selecting a physical uplink control channel (PUCCH) resource based inpart on an index of one or more control channel elements (CCE) in one ormore physical downlink control channel (PDCCHs), wherein transmittingthe HARQ-ACK feedback comprises transmitting the HARQ-ACK feedback onthe selected PUCCH resource.
 15. A method for wireless communication bya network entity, comprising: sending a first configuration message anda second configuration message to a user equipment (UE), wherein: thefirst configuration message, in part, configures the UE to communicatecoordinated transmissions with a plurality of transmission receptionpoints (TRPs) using a coordinated transmission mode, the secondconfiguration message includes an indication of a first hybrid automaticrepeated request acknowledgment (HARQ-ACK) feedback mode or a secondHARQ-ACK feedback mode, and the first configuration message and thesecond configuration message are radio resource control (RRC) messages;transmitting one or more physical downlink shared channel (PDSCH)transmissions from the plurality of TRPs in accordance with thecoordinated transmission mode; determining a HARQ-ACK feedback mode,selected from at least the first HARQ-ACK feedback mode and secondHARQ-ACK feedback mode, based on the indication in the secondconfiguration message; and receiving HARQ-ACK feedback for the at leastone or more PDSCH transmissions to at least one of the plurality of TRPsusing the determined HARQ-ACK feedback mode.
 16. The method of claim 15,wherein: the first HARQ-ACK feedback mode comprises a joint HARQ-ACKfeedback mode; and the second HARQ-ACK feedback mode comprises aseparate HARQ-ACK feedback mode.
 17. The method of claim 16, wherein theHARQ-ACK feedback is based a joint codebook when the first HARQ-ACKfeedback mode is selected.
 18. The method of claim 15, wherein thecoordinated transmission mode is one of: a first mode comprising aphysical downlink control channel (PDCCH) and a PDSCH, wherein the PDSCHcomprises different spatial layers from different TRPs; or a second modecomprising a first PDCCH, a second PDCCH, a first PDSCH and a secondPDSCH, wherein the first PDSCH is transmitted from a first TRP, and thesecond PDSCH is transmitted from a second TRP, and the first PDSCH andthe second PDSCH carry different transport blocks (TBs).
 19. The methodof claim 18, wherein: when the coordinated transmission mode is one of afirst set of transmission modes including the first mode, determiningthe HARQ-ACK feedback mode comprises selecting the first HARQ-ACKfeedback mode; and when the coordinated transmission mode is one of asecond set of transmission modes including the second mode, determiningthe HARQ-ACK feedback mode comprises selecting the first HARQ-ACKfeedback mode or the second HARQ-ACK feedback mode based at least inpart on one or more parameters provided to the UE.
 20. The method ofclaim 19, wherein: the one or more parameters indicate a backhaulcondition; and when the parameters indicate a high performance backhaulcondition, determining the HARQ-ACK feedback mode comprises selectingthe first HARQ-ACK feedback mode, and when the parameters indicate a lowperformance backhaul condition, determining the HARQ-ACK feedback modecomprises selecting the second HARQ-ACK feedback mode.
 21. The method ofclaim 15, wherein the configuration message in part indicates at leastone downlink control information (DCI) indicative of a first codebook.22. The method of claim 21, wherein the at least one DCI is indicativeof the first HARQ-ACK feedback mode or the second HARQ-ACK feedbackmode.
 23. The method of claim 22, wherein: when the at least one DCI isindicative of a first codebook and the first codebook is indicative ofthe second HARQ-ACK feedback mode, determining the HARQ-ACK feedbackmode comprises the second HARQ-ACK feedback mode.
 24. The method ofclaim 15, further comprising: determining a physical uplink controlchannel (PUCCH) resource based in part on an index of one or morecontrol channel elements (CCE) in one or more physical downlink controlchannels (PDCCHs); and monitoring the determined PUCCH resource for theHARQ-ACK feedback.
 25. An apparatus for wireless communication,comprising: at least one processor coupled with a memory and configuredto: receive a first configuration message and a second configurationmessage, wherein: the first configuration message, in part, configures auser equipment (UE) to communicate coordinated transmissions with aplurality of transmission reception points (TRPs) using a coordinatedtransmission mode, the second configuration message includes anindication of a first hybrid automatic repeated request acknowledgment(HARQ-ACK) feedback mode or a second HARQ-ACK feedback mode, and thefirst configuration message and the second configuration message areradio resource control (RRC) messages; receive one or more physicaldownlink shared channel (PDSCH) transmissions from the plurality of TRPsin accordance with the coordinated transmission mode; select a HARQ-ACKfeedback mode, from at least first HARQ-ACK feedback mode and the secondHARQ-ACK feedback mode, based on the indication in the secondconfiguration message; and transmit HARQ-ACK feedback for the at leastone or more PDSCH transmissions to at least one of the plurality of TRPsusing the selected HARQ-ACK feedback mode.
 26. The apparatus of claim25, wherein: the first HARQ-ACK feedback mode comprises a joint HARQ-ACKfeedback mode; and the second HARQ-ACK feedback mode comprises aseparate HARQ-ACK feedback mode.
 27. An apparatus for wirelesscommunication, comprising: at least one processor coupled with a memoryand configured to: send a first configuration message and a secondconfiguration message to a user equipment (UE), wherein: the firstconfiguration message, in part, configures the UE to communicatecoordinated transmissions with a plurality of transmission receptionpoints (TRPs) using a coordinated transmission mode, the secondconfiguration message includes an indication of a first hybrid automaticrepeated request acknowledgment (HARQ-ACK) feedback mode or a secondHARQ-ACK feedback mode, and the first configuration message and thesecond configuration message are radio resource control (RRC) messages;transmit one or more physical downlink shared channel (PDSCH)transmissions from the plurality of TRPs in accordance with thecoordinated transmission mode; determine a HARQ-ACK feedback mode,selected from at least a first HARQ-ACK feedback mode and a secondHARQ-ACK feedback mode, based on the indication in the secondconfiguration message; and receive HARQ-ACK feedback for the at leastone or more PDSCH transmissions to at least one of the plurality of TRPsusing the determined HARQ-ACK feedback mode.